1. Field
The presently disclosed subject matter relates to vehicle decorative lighting devices and vehicle lamps including the decorative lighting device and lamps, and more particularly to the vehicle decorative lighting devices having a favorable light distribution with a simple structure, which can be substantially incorporated along an outer periphery of a vehicle lamp. Thus, a vehicle lamp that includes the decorative lighting device can have a high visual quality, which can emit harmonious light with respect to other lighting devices or lamps, and the decorative lighting lamps can be used as a position lamp when the vehicle lamps are used as a headlight.
2. Description of the Related Art
Various vehicle lamps, including decorative lighting devices that form secondary light distributions, are known as a vehicle lamp, including headlights. For example, a conventional decorative lighting device for vehicles, which can be incorporated into a vehicle lamp such as a headlight, is disclosed in Patent Document No. 1 (U.S. Pat. No. 5,984,497), which is owned by Applicant of this disclosed subject matter.
FIG. 4 is a perspective view depicting a conventional vehicle lamp including a decorative lighting device disclosed in Patent Document No. 1. The conventional vehicle lamp 10 may incorporate a headlight unit 14 along with the conventional decorative lighting device 15 in a lamp room formed between a housing 12 and an outer lens 13. The vehicle lamp 10 may be attached to a front and left portion of a vehicle from a traveling directional view of the vehicle. Another vehicle lamp attached to a front and right portion of the vehicle may be symmetrical to the vehicle lamp 10.
The conventional vehicle lamp 10 may include: the housing 12 having an opening located in a light-emitting direction of the vehicle lamp 10, and the opening inclining from a right (a middle direction of a vehicle) toward a left (a side direction of a vehicle) in an upper right direction from a front view of the vehicle lamp 10 and inclining in a rear direction of the vehicle lamp 10 from a side view of the vehicle lamp 10; the outer lens 13 made from a transparent plate, and covering the opening of the housing 12; the lamp room located between the outer lens 13 and the housing 12; the headlight unit 14 located in the lamp room so as to emit light in the light-emitting direction of the vehicle lamp 10 via the outer lens 13; and the decorative lighting device 15 located in the lamp room and along a periphery of the opening of the housing 12 so as to emit light via the outer lens 13.
FIG. 5a is a schematic front view showing the conventional decorative lighting device 15, which is incorporated into the vehicle lamp 10 shown in FIG. 4. The vehicle decorative light device 15 may include a light guide lens 16 having a first end surface 16A and a second end surface 16B, which is formed in a substantially slender U-shape, and a pair of light sources 17 located at the first and second end surfaces 16A and 16B so that each of lighting-emitting surfaces of the light sources 17 faces a respective one of the first and second end surfaces 16A and 16B.
As each of the pair of light sources 17, a light-emitting diode (LED) light source such as a white LED light source, a yellow LED light source, an amber LED light source, a red LED light source and the like can be used depending on the intended use of the decorative lighting device 15. For example, semiconductor light-emitting devices that can emit various color lights as disclosed in Patent Document No. 2 (U.S. Pat. No. 8,461,610), which is owned by Applicant of this disclosed subject matter, can be used as the LED light source.
The light guide lens 16, which is formed in a substantially laterally-facing U-shape, may include: a first linear portion 16L having the first end surface 16A located at a top portion of the light guide lens 16 and linearly extending in an extending direction of the light guide lens 16; a second linear portion 16M having the second end surface 16B located at a bottom portion of the light guide lens 16 and linearly extending in the extending direction of the light guide lens 16; a first curved portion 16R1 having a first curvature radius R1 at a central axis thereof continuously connecting to the first linear portion 16L and extending toward the second linear portion 16M; a second curved portion 16R2 having a second curvature radius R2 at a central axis thereof continuously connecting to the second linear portion 16M and extending toward the first curved portion 16R1; and a third linear portion 16N linearly extending in the extending direction of the light guide lens 16, and continuously connected between the first curved portion 16R1 and the second curved portion 16R2 so as to extend in a top and bottom direction of the light guide lens 16.
Each of the first and second end surfaces 16A and 16B may be formed in a planar shape so as to be substantially perpendicular to an outer surface and an inner surface of the light guide lens 16 in order for the light guide lens 16 to efficiently receive light emitted from the pair of light sources 17. FIG. 5b is a partial enlarged cross-sectional view depicting the light guide lens 16 used for the decorative lighting device 15, wherein the light guide lens 16 is shown as a partial enlarged cross-sectional view at a right angle with respect to an extending direction 16X of the light guide lens 16 between the first and second end surfaces 16A and 16B shown in FIG. 5a. A cross-sectional shape of the light guide lens 16 in a direction perpendicular to the extending direction 16X may be substantially rectangular.
Accordingly, a front surface of the light guide lens 16, which faces the outer lens as described in FIG. 4, may be formed in a substantially planar shape between the first and second end surfaces 16A and 16B so as to be parallel to a substantially rear surface of the light guide lens 16, which is located opposite the front surface. However, the light guide lens 16 may include a plurality of prism faces 16P on the rear surface, which is formed in a substantially planar shape. The plurality of prism faces 16P may be arranged in a longitudinal direction (16X) of the light guide lens 16, and each of the prism faces 50 may extend in a direction of a wide direction. Each cross-sectional shape of the prism faces 16P in the extending direction 16X of the light guide lens 16 may be formed in a substantially triangle shape having an apex 16T.
The light emitted from the light sources 17 may enter into the light guide lens 16 from each of the first and second end surfaces 16A and 16B, and may move in the extending direction 16X of the light guide lens 16 while it repeats internal reflections in the light guide lens 16. In this case, the light emitted from the light sources 17 may be reflected by the prism faces 16P, which are arranged in the longitudinal direction of the light guide lens 16, and may be emitted from the front surface of the light guide lens 16 and over the entire length of the light guide lens 16.
Thereby, the light guide lens 16 of the decorative lighting device 15, which is located along the periphery of the opening of the housing 12 as shown in FIG. 4, may provide a light distribution as the vehicle decorative lighting device via the outer lens 13 from the front surface of the light guide lens 16, which is the light-emitting surface of the vehicle decorative lighting device 15. In this case, as light that has entered into the light guide lens 16 from each of the first and second end surfaces 17A and 17B repeats the internal reflections in the first linear portion 16L and the second linear portion 16M, a primary light flux having a larger incident angle in a moving direction of the light may relatively decrease in the moving light, and a secondary light flux having a smaller incident angle in the moving direction of the light may relatively increase in the moving light.
Therefore, light that has entered into the first linear portion 16L from the first end surface 16A can move in the first linear portion 16L, in which a length in the extending direction X of the first linear portion 16L is longer than that of the second linear portion 16M, and therefore can enter into the first curved portion 16L in a state such that a ratio of the secondary light flux to the primary light flux is relatively large. As a result, the light that has entered into the first linear portion 16L from the first end surface 16A may smoothly move in the first curved portion 16R1 while preventing a leaked light from the first curved portion 16L in spite of a structure that the first curved portion 16L includes a small curvature radius such as a first curvature radius R1, and the light may be efficiently emitted from the front surface of the first curved portion 16L having the curvature radius R1.
Meanwhile, light that has entered into the second linear portion 16M from the second end surface 16B may move in the second linear portion 16M, and therefore may enter into the second curved portion 16R2 in a state such that a ratio of the secondary light flux to the primary light flux is relatively small. However, the light that has entered into the second linear portion 16M from the second end surface 16B may smoothly move in the second curved portion 16M while preventing a leaked light from the second curved portion 16M, and also may be efficiently emitted from the front surface of the second curved portion 16R2 having the curvature radius R2.
The above-described decorative lighting device 15 is formed in the substantially slender U-shape, and is located along the peripheral portion of the housing. Accordingly, the conventional decorative lighting device 15 may provide a high visibility and an attractive appearance. In contrast, the conventional decorative lighting device 15 may be subject to a complex structure because of the light sources 17 located adjacent the first and second end surfaces 16A and 16B, etc. Hence, a conventional vehicle lamp using a light guide, which be illuminated by entering light from an end of the light guide, is disclosed in Patent document No. 3 (Japanese Patent Application Laid Open JP 2010-272469).
FIG. 6a is a schematic front view showing the conventional vehicle lamp using a plurality of light guides, and FIG. 6b is a normal cross-sectional view in a wide direction of one of the light guides included in the vehicle lamp, which is disclosed in Patent document No. 3. The conventional vehicle lamp 20 includes: a lamp body 21: a light source holder 24 having light-emitting diodes (LEDs) 24L attached to the lamp body 21 via a fixing portion 23, and the LEDs 24L projecting from the light source holder 24 along the lamp body 21; an alignment block 25 attached to the light source holder 24; the plurality of light guides 22 each having an end surface connecting the alignment block 25, each of the end surfaces thereof facing a respective one of the LEDs 24L, and each of the light guides 22 extending in an opposite direction of the respective one of the LEDs 24L in parallel with respect to each other; and an outer lens 26 attached to the lamp body 21, wherein light emitted from the respective one of the LEDs 24L is emitted from the outer lens 26 via each of the light guides 22.
As shown in FIG. 6b, the light guide 22 includes a light-emitting surface 22A having a central axis 22AC formed in a convex shape, the central axis 22AC extending from a rear surface 22B at a right angle with respect to the rear surface 22B toward an apex of the convex shape, extending along the rear surface 22B at the right angle and the apex of the concave shape and therefore being formed in a planar shape. The rear surface 22B of the light guide 22 includes a prism surface 22BP, which is arranged in a longitudinal direction of the light guide 22 and extends in a wide direction of the light guide 22.
Accordingly, the lights emitted from the respective one of the LEDs 24L may be emitted from the outer lens 26 via each of the light guides 22, in which each of the end surfaces of the light guides 22 faces the respective one of the LEDs 24L, in common with the conventional decorative lighting device 15 incorporated into the conventional vehicle lamp 10 shown in FIG. 4.
However, the conventional vehicle lamp 20 includes the plurality of light guides 22 extending in parallel with respect to each other and the respective one of the LEDs 24L facing each of the end surfaces of the light guides 22. Each of the light guides 22 is formed in a linear shape, and also a respective one of optical axes of the LEDs 24L may generally correspond to with each of the central axes 22AC of the light guides 22 to improve optical characteristics such as a light-emitting efficiency, etc.
Accordingly, each of the light guides 22 may tend to heighten a light-intensity near each of the central axes 22AC as compared with other regions of each of the light guides 22, and therefore may cause a color variability on a light-emitting surface of each of the light guides 22 when such a structure is used as a light source for the decorative lighting device.
The above-referenced Patent Documents and additional Patent Documents are listed below and are hereby incorporated with their English specifications and abstracts in their entireties.
1. Patent Document No. 1: U.S. Pat. No. 8,870,423
2. Patent Document No. 2: U.S. Pat. No. 8,461,610
3. Patent Document No. 3: Japanese Patent Application Laid Open JP 2010-272,469
4. Patent Document No. 4: U.S. Pat. No. 8,786,804
The disclosed subject matter has been devised to consider the above and other problems, characteristics and features. Thus, exemplary embodiments of the disclosed subject matter can include vehicle decorative lighting devices which can provide a favorable light distribution having a high visibility and a high visual quality with a simple structure, and which can expand possibilities for design so as to be able to harmonize with various vehicle lamps including a vehicle decorative lighting device.
In addition, exemplary embodiments of the disclosed subject matter can include vehicle decorative lighting devices which can emit various color lights using an LED light source having a low power consumption such that the lighting devices can be incorporated into various vehicle lamps such as a headlight, a turn signal lamp, a stop lamp, etc. In this case, when the vehicle lamp is a headlight such that a white LED light source or an HID bulb is used as a light source, the vehicle decorative lighting device can emit a harmonious white light with light emitted from the headlight so as to be usable as a position lamp and the like. Also, when the vehicle lamp is configured as a stop lamp such that a red LED light source is used as a light source, the vehicle decorative lighting device can emit a harmonious red light with light emitted from the stop lamp so as to be usable as a tail lamp, etc.